There has been a VHS cassette adapter as shown in FIG. 6, where a C-cassette 25 is inserted in an adapter 26 which has a same size as that of a full-size VHS cassette playable on a magnetic recording/reproducing apparatus.
In the adapter, C-cassette 25 is mounted in adapter 26 from the top surface with a tape protection lid 27 of the C-cassette open, and a protection cover in the top surface of adapter 26 is closed for operation. A reel brake (not shown) of C-cassette 25 is released when a C-cassette is mounted in the adapter 26 by a lock releasing pin (not shown) provided on adaptor 26.
After the protection cover of adapter 26 is closed, tape 28 is pulled out of C-cassette 25 by a pulling post 29 to be placed to a same position as that of the full-size cassette in preparation for loading in a magnetic recording/reproducing apparatus.
As the adapter 26 incorporating a C-cassette 25 assumes an exactly the same shape and function as a full-size VHS cassette, no extra switching gear needs to be provided in a magnetic recording/ reproducing apparatus for recording and reproducing with the adapter.
In the professional digital video format, there are two cassette forms; an S-cassette (S signifies small; a first cassette in the present invention) and an M-cassette of different size (M signifies middle; a second cassette in the present invention). If the same structure as in the VHS format is introduced for the professional digital video version, problems arise. Namely, as the space between the reels is small in the S-cassette and the M-cassette, the coupling of reel movement will become very complicated when forming a cassette adapter (for adapting an S-cassette for the M-cassette shape) with the reel placed in the same position as that of the M-cassette. Furthermore, if reel brake is released when an S-cassette is mounted in an adapter the reel is left unlocked and tape becomes loose inviting a damage.
Difference in the level of top surface between S-cassette and M-cassette is Imm. Therefore it is difficult to provide a protection cover on the top surface of an adapter for covering S-cassette; which means that an S-cassette can not be mounted in from the top surface, and it becomes very difficult to couple the identification terminal and the anti-erasing gear of an S-cassette with the counterparts of the adapter which are disposed in the places corresponding to those of the M-cassette.
Furthermore, because both the cassette adapter and the M-cassette assume an identical shape it is impossible for a magnetic recording/ reproducing apparatus to judge whether the one being loaded is a cassette adapter or an M-cassette. Therefore, in a case when a cassette adapter is loaded in a magnetic recording/reproducing apparatus which is incompatible with adapter, there will be a possiblity of broken equipment.